This invention relates in general to entrance systems and, more particularly, to an automatic sliding door entrance. The invention is particularly concerned with an entrance system having solid-state electronic control circuitry for controlling the energization of a d.c. electrical motor for operating doors of the system.
An object of the invention is the provision of a solid-state electronic door control system having a d.c. electric motor for operating a door and a semiconductor device for supplying d.c. power to the motor wherein speed control of the motor is effected by sensing the counterelectromotive force developed by the motor.
Another object of the invention is the provision of such an electronic door control system in which change in said counterelectromotive force produced by door blockage is sensed to cause d.c. power supplied to the motor to be reduced for stopping door movement.
A further object of the invention is the provision of such an electronic door control system in which various positions of the door during opening or closing are sensed to change the level of d.c. power supplied to the motor for changing door movement speed accordingly.
A still further object of the present invention is the provision of such an electronic door control system in which door blockage during door closing is electronically sensed to cause a door opening and reclosing cycle to be initiated.
Another object of the present invention is the provision of such an electronic door control system in which nearly opened and nearly fully closed position of the door are electronically sensed and conductivity of the semiconductor device is effectively varied in order to reduce the motor speed and thereby a door speed at such positions.
It is a still further object of the present invention to provide an electronic door control system which embodies novel control means for causing variation in the speeds of door opening and door closing movements for promoting both safety and relatively repair-free longevity of use.
It is another object of the present invention to provide a system of the character stated which is readily adapted for doors of the double leaf or the single leaf type and which systems are particularly amenable to presentation in attractive, ornamental design.
It is a still further object of the present invention to provide a system of the character stated which is constituted of relatively few components, all of which are of durable, wear-resistant construction; and which system incorporates easily manipulated means for appropriately adjusting components to assure of effective operation of the system without requiring the customary dismantling procedure with attendant down-time.